Spectacle lens

ABSTRACT

Provided is an eyeglass lens 1 configured to cause rays that have entered from an object-side surface 3 to be emitted from an eyeball-side surface 4, and cause the emitted rays to converge at a predetermined position A. The eyeglass lens 1 includes a lens base material 2 having a plurality of base material convex portions 6 on at least one of the object-side surface 3 and the eyeball-side surface 4, and a coating film covering the surface provided with the base material convex portions 6. The shape of convex portions present on the outermost surface of the eyeglass lens located on a side on which the base material convex portions 6 are provided is an approximate shape of the base material convex portions configured to cause rays that have entered the eyeglass lens 1 to converge at a position B that is closer to the object than the predetermined position A is.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/JP2019/025616, filed Jun. 27, 2019, which claims priority toJapanese Patent Application No. 2018-125123, filed Jun. 29, 2018, andthe contents of which is incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an eyeglass lens.

BACKGROUND ART

Patent Document 1 (US Publication No. 2017/131567) discloses an eyeglasslens for suppressing the progression of a refractive error such asnear-sightedness. Specifically, for example, a spherical minute convexportion (a base material convex portion in this specification) with adiameter of about 1 mm is formed on a convex surface, which is theobject-side surface of the eyeglass lens. With an eyeglass lens,normally, rays that have entered from the object-side surface areemitted from the eyeball-side surface and thus are focused on thewearer's retina (a predetermined position A in this specification). Onthe other hand, as for light that has passed through the minute convexportion, rays that are incident on the eyeglass lens are focused at aposition B closer to the object than the predetermined position A is. Asa result, the progression of near-sightedness is suppressed.

CITATION LIST Patent Documents

-   Patent Document 1: US Publication No. 2017/131567

SUMMARY OF DISCLOSURE Technical Problem

The inventor of the present disclosure found that, if a coating film(e.g., a hard coating film or an antireflection film), which is the sameas a conventional coating film, is formed on a surface (a convexsurface, which is the object-side surface), which is provided with theminute convex portion, of the eyeglass lens disclosed in Patent Document1, the function of suppressing the progression of near-sightedness maydeteriorate.

One embodiment of the present disclosure aims to provide a technique bywhich the effect of suppressing near-sightedness can be sufficientlyexhibited even after a coating film is formed on a lens base material.

Solution to Problem

The inventor of the present disclosure conducted intensive studies toresolve the above-described issues. The coating film covers a surfacehaving the base material convex portion. In this case, the outermostsurface shape of the coating film has a coating film convex portionoriginating from the base material convex portion.

If no coating film is provided, rays are focused due to the basematerial convex portion at a position closer to the object than thepredetermined position A is. However, if a coating film is formed on thelens base material, whether rays are focused on the same position asthat of the base material convex portion or the vicinity thereof dependson the outermost surface shape of the coating film, that is, the shapeof the coating film convex portion.

In view of this, the inventor of the present disclosure conceived thefollowing methods.

The inventor found that, if the shape of a convex portion on theoutermost surface of an eyeglass lens is an approximate shape of a basematerial convex portion, the effect of suppressing near-sightedness canbe sufficiently exhibited. Preferably, the shape of a base materialconvex portion (i.e., a partially spherical shape) is virtualized fromthe shape of an actual coating film convex portion. The inventor foundthat the effect of suppressing nearsightedness can be further exhibitedwhen a difference between the shape of a virtual partial sphere and theshape of the actual coating film convex portion is kept at apredetermined value.

The present disclosure was made based on the above-described findings.

A first aspect of the present disclosure is an eyeglass lens configuredto cause rays that have entered from an object-side surface to beemitted from an eyeball-side surface, and cause the emitted rays toconverge at a predetermined position A, the eyeglass lens including:

a lens base material having a plurality of base material convex portionson at least one of the object-side surface and the eyeball-side surface;and

a coating film covering the surface provided with the base materialconvex portions,

in which a shape of convex portions present on the outermost surface ofthe eyeglass lens located on a side on which the base material convexportions are provided is an approximate shape of the base materialconvex portions configured to cause rays that have entered the eyeglasslens to converge at a position B that is closer to the object than thepredetermined position A is.

A second aspect of the present disclosure is an aspect according to thefirst aspect,

in which a shape of the outermost surface of the coating film includes acoating film convex portion originating from the base material convexportions,

the coating film convex portion is configured to cause rays that haveentered the eyeglass lens to converge at the position B that is closerto the object than the predetermined position A is, and

the maximum absolute value of differences in a lens thickness directionbetween a spherical surface that is optimally approximated to a shape ofthe coating film convex portion and the shape of the actual coating filmconvex portion is 0.1 μm or less.

A third aspect of the present disclosure is an aspect according to thesecond aspect,

in which the coating film convex portion is configured to cause raysthat have entered the eyeglass lens to converge at the position B thatis closer to the object than the predetermined position A is by anamount in a range of more than 0 mm and 10 mm or less.

A fourth aspect of the present disclosure is an aspect according to thesecond or third aspect, in which, out of a large number of rays that canbe obtained by ray tracing calculation, evenly enter a predeterminedrange of the object-side surface of the eyeglass lens, and pass throughthe coating film, the number of stray light rays that do not passthrough the vicinity of the predetermined position A or the vicinity ofthe position B that is closer to the object is less than or equal to 30%of the number of incident rays.

A fifth aspect of the present disclosure is an aspect according to anyof the second to fourth aspects,

in which a profile curve of astigmatism at a base of the coating filmconvex portion in an astigmatism distribution for the shape of theoutermost surface of the coating film is 0.20 mm or less.

A sixth aspect of the present disclosure is an aspect according to anyof the first to fifth aspects,

in which the coating film includes a λ/4 film that is in contact withthe lens base material, a hard coating film formed on the λ/4 film, andan antireflection film formed on the hard coating film.

A seventh aspect of the present disclosure is an aspect according to thesixth aspect,

in which a refractive index of the lens base material is higher thanthat of the λ/4 film, and a refractive index of the λ/4 film is higherthan that of the hard coating film.

Advantageous Effects of Disclosure

According to one embodiment of the present disclosure, the effect ofsuppressing near-sightedness can be sufficiently exhibited even after acoating film is formed on a lens base material.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing one example of an eyeglass lensaccording to one aspect of the present disclosure.

FIG. 2 is a schematic side sectional view showing how an eyeglass lensaccording to one aspect of the present disclosure causes rays that haveentered from the object-side surface to be emitted from the eyeball-sidesurface due to a portion other than the coating film convex portions(that is, the base portion), and causes the emitted rays to converge ata predetermined position A on the retina of the eyeball.

FIG. 3 is a schematic side sectional view showing how an eyeglass lensaccording to one aspect of the present disclosure causes rays that haveentered from the object-side surface to be emitted from the eyeball-sidesurface due to a coating film convex portion, and causes the emittedrays to converge at a position B that is closer to the object than thepredetermined position A is.

FIG. 4 is a schematic cross-sectional view showing a coating film convexportion of an actual eyeglass lens and the shape of a virtual partialsphere.

FIG. 5 is a flowchart showing the flow of a method for inspecting aneyeglass lens according to one aspect of the present disclosure.

FIG. 6 is a diagram (No. 1) illustrating a method for specifying aposition on which rays are concentrated.

FIG. 7 is a diagram (No. 2) illustrating a method for specifying aposition on which rays are concentrated.

FIG. 8 is a diagram (No. 3) illustrating a method for specifying aposition on which rays are concentrated.

FIG. 9 is a flowchart illustrating a method for specifying a position onwhich rays are concentrated.

FIG. 10 is a diagram showing a plot (solid line) of, with regard todesigned values (i.e., no coating film), the astigmatism distribution(i.e., an astigmatism profile curve) on a cross-section passing throughthe vertex of a base material convex portion (i.e., the center of thebase material convex portion in a plan view), in the astigmatismdistribution with respect to the base material convex portion and thevicinity thereof.

FIG. 11 is a diagram showing a plot (solid line) of the astigmatismdistribution (i.e., an astigmatism profile curve) on a cross-sectionpassing through the vertex of a coating film convex portion (i.e., thecenter of the coating film convex portion in a plan view), in theastigmatism distribution with respect to an actual coating film convexportion and the vicinity thereof.

FIG. 12A is a schematic cross-sectional view showing a coating filmconvex portion and a base material convex portion of an actual eyeglasslens. FIG. 12B is a schematic cross-sectional view in which the vertexof the coating film convex portion and the vertex of the base materialconvex portion are matched.

DESCRIPTION OF EMBODIMENTS

The following describes embodiments of the present disclosure. Thedescription below is exemplary, and the present disclosure is notlimited to the aspects that are described as examples.

FIG. 1 is a cross-sectional view showing one example of an eyeglass lens1 according to one aspect of the present disclosure.

An example is shown in FIG. 1 in which an object-side surface 3 is aconvex surface, and an eyeball-side surface 4 is a concave surface (anexample of so-called meniscus lens).

The eyeglass lens 1 according to one aspect of the present disclosurehas the object-side surface 3 and the eyeball-side surface 4. The“object-side surface 3” is the surface that is located on the objectside when a wearer wears the glasses including the eyeglass lens 1. The“eyeball-side surface 4” is the surface that is located on the oppositeside, that is, the eyeball side, when the wearer wears the glassesincluding the eyeglass lens 1.

With the eyeglass lens 1 according to one aspect of the presentdisclosure, similarly to a conventional eyeglass lens 1, the baseportion other than the minute convex portions (i.e., the base materialconvex portions 6 and the coating film convex portions 11 thereon)disclosed in Patent Document 1 functions to cause rays that have enteredfrom the object-side surface 3 to be emitted from the eyeball-sidesurface 4 and to cause the emitted rays to converge at the predeterminedposition A.

FIG. 2 is a schematic side sectional view showing how the eyeglass lens1 according to one aspect of the present disclosure causes rays thathave entered from the object-side surface 3 to be emitted from theeyeball-side surface 4 and causes the emitted rays to converge at thepredetermined position A located on a retina 20A of an eyeball 20, dueto a portion (i.e., the base portion) other than the coating film convexportions 11.

The eyeglass lens 1 according to one aspect of the present disclosureincludes a lens base material 2. The lens base material 2 also has anobject-side surface 3 and an eyeball-side surface 4. The shape of bothsurfaces of the lens base material 2 may be determined according to thetype of eyeglass lens 1, and may be a convex surface, a concave surface,a flat surface, or a combination thereof.

The eyeglass lens 1 is formed by forming a coating film to cover atleast one of the object-side surface and the eyeball-side surface of thelens base material 2.

A plurality of base material convex portions 6 are formed on at leastone of the object-side surface 3 and the eyeball-side surface 4 of thelens base material 2 according to one aspect of the present disclosure.In a state in which the coating film is formed on the base materialconvex portions 6 and the coating film convex portions 11 originatingfrom the base material convex portions 6 are formed on the outermostsurface of the coating film, the coating film convex portions 11 causerays that have entered the eyeglass lens 1 to converge at a position Bthat is closer to the object than the predetermined position A is.

FIG. 3 is a schematic side sectional view showing how the eyeglass lens1 according to one aspect of the present disclosure causes rays thathave entered from the object-side surface 3 to be emitted from theeyeball-side surface 4 due to the coating film convex portions 11, andcauses the emitted rays to converge at the position B that is closer tothe object than the predetermined position A is. Note that thisconvergence position B is present as positions B₁, B₂, B₃, . . . B_(N)according to the plurality of coating film convex portions 11. Theconvergence position B in this specification is an expression of thecollection of the positions B₁, B₂, B₃, . . . B_(N).

In one aspect of the present disclosure, the shape of a convex portion(e.g., the coating film convex portion 11) on the outermost surface ofthe eyeglass lens located on the side on which the base convex portions6 are provided is an approximate shape of the base convex portionconfigured to cause rays that have entered the eyeglass lens to convergeat the position B that is closer to the object than the predeterminedposition A is.

The approximate shape of the base material convex portion refers to ashape in a state in which a spherical surface (referred to as the shapeof a virtual partial sphere hereinafter) that is optimally approximatedto the shape of the coating film convex portion 11 and the shape of thebase material convex portion 6 are approximated to each other.

One specific example of the approximate shape of the base materialconvex portion is as follows. It is preferable that the maximum absolutevalue of the differences in the lens thickness direction between thespherical surface that is optimally approximated to the shape of thecoating film convex portion 11 and the shape of the actual coating filmconvex portion 11 is 0.1 μm or less (preferably, 0.06 μm or less).

The following describes advantages in defining the shape of a virtualpartial sphere and the difference.

If no coating film is provided, the base material convex portions 6 havea substantially partially spherical shape, and rays are focused at theposition B that is closer to the object. Even if a coating film isformed on the lens base material 2 and the coating film convex portion11 has a more obtuse shape than the base material convex portion 6 does,at least a vertex portion of the coating film convex portion 11 has ashape following the base material convex portion 6.

In one aspect of the present disclosure, based on a substantiallypartially spherical shape of the vertex portion of the coating filmconvex portion 11, a spherical surface that is optimally approximated tothis substantially partially spherical shape is virtualized.Accordingly, a virtual partially spherical shape is obtained. Then, thevirtual partially spherical shape is compared to the shape of the actualcoating film convex portion 11.

FIG. 4 is a schematic cross-sectional view showing the coating filmconvex portion 11 of the actual eyeglass lens 1 and the virtualpartially spherical shape. The solid line indicates the coating filmconvex portion 11 of the actual eyeglass lens 1, and the broken lineindicates the virtual partially spherical shape, the dash-dot lineindicates a base portion of the actual eyeglass lens 1, and a horizontalportion indicates the difference between the virtual partially sphericalshape and the shape of the actual coating film convex portion 11 in thelens thickness direction.

The virtual partially spherical shape refers to a partial shape of asphere that is optimally approximated to the shape of the coating filmconvex portion 11 of the actual eyeglass lens 1. This virtual partiallyspherical shape can be obtained using the method of least squares, forexample.

One specific example of optimal approximation is as follows. A sphericalshape is disposed to overlap the shape of the coating film convexportion 11. The difference in the lens thickness direction (an opticalaxis method, the Z-axis) between the two shapes of portions whoseprotrusions start from the base portion on the outermost surface of theeyeglass lens 1 and end at the base portion through the vertex issquared. A virtual partially spherical shape that minimizes the sum ofthese values is set.

As a method other than the method of least squares, the virtualpartially spherical shape may be obtained from a plurality of positionsof the vertex of the coating film convex portion 11 and the vicinitythereof. In this case, the difference may be examined by matching thevertex of the virtual partially spherical shape with the vertex of thecoating film convex portion 11 of the actual eyeglass lens 1.

If the maximum absolute value of the differences is 0.1 μm or less(preferably, 0.06 μm or less), the coating film convex portion 11 isvery close to the partially spherical shape. As a result, the effect ofsuppressing near-sightedness can be sufficiently exhibited. Furthermore,when this specification is applied, the effect of suppressingnear-sightedness can be significantly exhibited, and the need to exposea cross-section of the actually produced eyeglass lens 1 and checkwhether or not the shape of the coating film convex portion canfaithfully reflect the shape of the base material convex portion iseliminated.

A point where a curve, which is obtained by curving the shape of thecoating film convex portion 11 and differentiating the obtained curveonce, has increased may be used as the protrusion start portionprotruding from the base portion on the outermost surface. Also, a peakrising portion that rises from the astigmatism profile curve shown inFIG. 11(b), which will be described later, may be used as the protrusionstart portion. The protrusion end portion may be set in the same manner.

The following describes further specific examples of one aspect of thepresent disclosure, preferred examples, and variations.

In one aspect of the present disclosure, out of a large number of raysthat can be obtained by ray tracing calculation, evenly enter apredetermined range of an object-side surface of an eyeglass lens, andpass through the coating film, the number of stray light rays that donot pass through the vicinity of the predetermined position A or thevicinity of the position B that is closer to the object is preferablyset to 30% or less of the number of incident rays.

The following describes advantages in reducing stray light rays and theratio of stray light rays.

Stray light rays are rays that enter from the object-side surface 3 ofthe eyeglass lens 1 and are emitted from the eyeball-side surface 4, andindicate rays that do not pass through the vicinity of the predeterminedposition A at which rays converge due to the eyeglass lens 1, and do notpass through the vicinity of the position B at which rays converge dueto the base material convex portions 6 and the coating film convexportions 11. Stray light rays cause blur in the wearer's visual field.Thus, it is preferable to reduce the ratio of stray light rays relativeto rays that enter from the object-side surface 3 of the eyeglass lens 1and are emitted from the eyeball-side surface 4.

One of the reasons for stray light rays is a coating film. If the shapeextending from the convex surface, which is the object-side surface 3serving as the base, changes excessively slowly at the base portion ofthe coating film convex portion 11, the resulting shape is differentfrom the spherical shape of the base material convex portion 6, and alsois different from the convex surface, which is the object-side surface3. Accordingly, rays will not be focused on the retina 20A of the wearer(the vicinity of the predetermined position A in this specification),and will not be focused in the vicinity of the position B that is closerto the object.

On the other hand, as with the eyeglass lens 1 of one aspect of thepresent disclosure, even after a coating film is formed on the lens basematerial 2, the effect of suppressing near-sightedness can besufficiently exhibited by setting the ratio of stray light rays to 30%or less.

Ray tracing calculation is used to set the ratio of stray light rays. Asituation in which a large number of rays evenly enter a predeterminedrange of the object-side surface of the eyeglass lens and pass throughthe coating film (i.e., a situation in which the eyeglass lens is wornand the wearer looks at the outside) is presumed in this calculation.This “predetermined range” needs only be an optical region on theobject-side surface. This “optical region” indicates a portion having acurved surface shape that realizes the power set for each wearer on theobject-side surface and the eyeball-side surface that is locatedopposite thereto.

Considering that one of the reasons for the occurrence of stray lightrays is a coating film and the eyeglass lens 1 according to one aspectof the present disclosure needs the coating film, the ratio of straylight rays may be set to more than 0% (or 1% or more, and 3% or more)and 30% or less. Also, because it is preferable to reduce the ratio ofstray light rays, the ratio of stray light rays is preferably set to 20%or less, and more preferably set to 15% or less.

Here, conditions under which the ratio of stray light rays is determinedwill be described below.

FIG. 5 is a flowchart showing the flow of a method for inspecting aneyeglass lens according to one aspect of the present disclosure.

As shown in FIG. 5, first, in step S101, the shape of the object-sidesurface (also referred to as “convex surface”) of the actual eyeglasslens 1 is measured, and curved surface data representing the shape ofthe convex surface 3 is generated (shape measurement step). The shape ofthe convex surface 3 is measured by a noncontact three-dimensionalmicroscope for measuring the length, utilizing interference of light,for example. The three-dimensional shape of the convex surface 3 isacquired as discrete three-dimensional data (x, y, z), for example.

Then, in step S102, curved surface data is generated from the obtaineddata indicating the shape of the convex surface of the eyeglass lens 1(curved surface data generation step). Note that, if discretethree-dimensional data is used as data indicating the shape of theconvex surface of the eyeglass lens 1, a set of B-spline curves needonly be generated. Also, if measured discrete three-dimensional dataincludes noise, moving average processing may be performed and anaverage value may be used, for example.

Then, in step S103, a model of the actual eyeglass lens 1 is set basedon the curved surface data (model setting step).

The model of the actual eyeglass lens 1 is set, and an eyeball model isalso set. Information relating to the wearer (e.g., the axial length andaccommodation amount of the eye) may be used for an eyeball model. Atthis time, an eyeglass lens model 30 may be disposed with respect to aneyeball model 32 in consideration of the inclination of the eyeglasslens when attached to the frame thereof (a forward tilt angle and aframe tilt angle).

Then, in step S104, the position at which rays converge most when therays have passed through the actual eyeglass lens 1 is specified througha ray tracing process (convergence position specifying step).Specifically, the PSF (Point Spread Function) representing the luminancedistribution obtained after rays emitted from an indeterminately distantlight source have passed through the model set based on the curvedsurface data of the actual eyeglass lens 1 is obtained.

The PSF can be obtained by trancing a large number of rays emitted fromthe point light source and calculating the density of spots on anyplane. Then, the position (plane) on which rays are most concentrated inany plane is specified by comparing the PSFs in the relevant plane. Notethat the diameter of rays need only be set based on the motion diameter,and may be set to 4φ, for example.

Here, a method for specifying, in step S104, the position on which raysare most concentrated will be described in more detail. FIGS. 6 to 8 arediagrams illustrating the method for specifying a position on which raysare concentrated. Also, FIG. 9 is a flowchart showing the method forspecifying a position on which rays are concentrated.

First, as shown in FIG. 6, in step S201, a situation is presumed inwhich rays pass through the coating film convex portion 36 of theobject-side surface (the convex surface) 33 on a model. Then,measurement planes P1,1 to P1,n are set at increments of a predeterminedseparation interval Δd (e.g., 0.1 mm) from a predetermined distance(e.g., a position located at about 16 mm, which is the thickness of thevitreous body) from a position of 0 mm on the retina 32A of the eyeballmodel 32 to the retina 32A. Note that the separation interval Δd may beset to an interval of 0.2 mm or 1/50 of the axial length of the eye.

Then, a ray tracing process is performed, and the densities of rays inthe measurement planes P1,1 to P1,n are calculated in step S202. Thedensities of rays need only be calculated by setting a lattice-shapedgrid (e.g., 0.1 mm×0.1 mm) to each measurement plane and calculating thenumber of rays passing through the grids, for example.

Then, in step S203, in order to specify a measurement plane where raysthat have entered the convex portion have the maximum density, in themeasurement planes P1,1 to P1,n, the measurement plane P1,i where rayshave the first local maximum density from the predetermined distance isspecified. In order to omit calculation, calculation of the ray densitymay be started from the measurement plane P1, and calculation of thisstep may be terminated when after the first local maximum density isdetected, the value obtained by calculating the ray density decreases toabout an intermediate value between the value in the measurement planeP1 and the first local maximum value.

Then, as shown in FIG. 7, in step S204, the measurement plane P2,1 andmeasurement plane P2,2 are set at positions located a separationdistance Δd/2 frontward and rearward from the measurement plane P1,iwith the maximum density. Then, the densities of rays in the measurementplane P2,1 and the measurement plane P2,2 are calculated in step S205. Ameasurement plane with the maximum density is specified in themeasurement planes P2,1, P2,2, and P1,i in step S206.

Then, in step S207, the same steps as steps S204 to S206 are repeateduntil the separation distance becomes significantly short. That is, asshown in FIG. 8, a step of setting a new measurement plane (P3,1 andP3,2 in FIG. 8) at a position located a new separation distance (Δd/4 inFIG. 8), which is half of the previous separation distance, forward andrearward from the measurement plane (P2,2 in FIG. 8) that previously hasthe maximum density, a step of calculating the density of rays in thenew measurement plane, and a step of specifying the measurement planethat previously has the maximum density and a measurement plane out ofthe new measurement planes that has the maximum are repeated.

It is possible to specify a position on which rays are concentrated inthe direction of the optical axis (the lens thickness direction, theZ-axis) through the above-described steps.

The position at which rays converge on a plane perpendicular to thedirection of the optical axis (i.e., on the specified measurement plane)is then specified. The above-described PSFs are used to specify thisposition. A portion (a point on the measurement plane) at which rays aremost concentrated is specified using the PSFs as a ray convergenceposition B on the measurement plane.

Also, the number of rays located outside a radius of 0.1 mm from the rayconvergence position B on the measurement plane is calculated, forexample. The inside of the radius of 0.1 mm from the convergenceposition B refers to the “vicinity of the position B” in thisspecification, for example.

Rays located inside a radius of 0.1 mm from the predetermined position Aat which rays converge due to the eyeglass lens 1 (i.e., normal raysthat converge at the position A) are subtracted from the rays outsidethe range. The inside of the radius of 0.1 mm from the convergenceposition A refers to the “vicinity of the position A” in thisspecification, for example.

The rays remaining after subtraction do not converge in the vicinity ofthe position A at which rays converge due to the eyeglass lens 1, and donot converge in the vicinity of the position B at which rays convergedue to the coating film convex portion 11 and that is closer to theobject. Such rays are referred to as stray light in this specification.Also, even after a coating film is formed on the lens base material 2,the effect of suppressing near-sightedness can be sufficiently exhibitedby setting the ratio of stray light rays to 30% or less.

It is preferable that the coating film convex portion 11 causes raysthat have entered the eyeglass lens 1 to converge at the position B thatis closer to the object than the predetermined position A is by anamount in a range of more than 0 mm and 10 mm or less. In other words,the outermost surface of the eyeglass lens 1 of one aspect of thepresent disclosure (i.e., the outermost surface of the coating film) hasa shape that causes rays that have entered the eyeglass lens 1 toconverge at the position B that is closer to the object than thepredetermined position A is by an amount in a range of more than 0 mmand 10 mm or less. Note that the above-described range is preferably 0.1to 7 mm, more preferably 0.1 to 5 mm, and even more preferably 0.3 to 3mm.

The relationship between a protruding length L_(c) of the coating filmconvex portion 11 and a protruding length L_(l) of the base materialconvex portion 6 preferably satisfies Formula (1) below.

0.6≤L _(c) /L _(l)≤1.5  Formula (1)

When this condition is satisfied, the coating film convex portion 11originating from the base material convex portion 6 can sufficientlybring the convergence position B of rays that have entered the eyeglasslens 1 closer to the object than the predetermined position A, even if acoating film is formed on the base material convex portion 6. This meansthat the coating film convex portion 11 and thus the eyeglass lens 1 ofone aspect of the present disclosure can exhibit a sufficientnear-sightedness suppression effect.

Note that a “protruding length” refers to the distance from the baseportion of the outermost surface shape of the eyeglass lens 1 to thevertex of the coating film convex portion 11 in the direction of theoptical axis (the lens thickness direction, the Z-axis).

It is preferable that the full width at half maximum of a profile curveof the astigmatism at the base of the coating film convex portion 11 inan astigmatism distribution with respect to the outermost surface shapeof the coating film is 0.20 mm or less.

FIG. 10 is a diagram showing a plot (solid line) of, with regard todesigned values (i.e., no coating film), the astigmatism distribution(i.e., an astigmatism profile curve) on a cross-section passing throughthe vertex of the base material convex portion 6 (i.e., the center ofthe base material convex portion 6 in a plan view), in the astigmatismdistribution with respect to the base material convex portion 6 and thevicinity thereof.

FIG. 11 is a diagram showing a plot (solid line) of the astigmatismdistribution (i.e., an astigmatism profile curve) on a cross-sectionpassing through the vertex of the coating film convex portion 11 (i.e.,the center of the coating film convex portion in a plan view), in theastigmatism distribution with respect to the actual coating film convexportion 11 and the vicinity thereof.

In FIGS. 10 and 11, the horizontal axis indicates the X-axis, i.e., aposition in the horizontal direction when the object-side surface 3 ofthe eyeglass lens 1 is viewed in a planar view, and the units thereofare in mm. The Y-axis, i.e., a vertical (up-down) direction when theobject-side surface 3 of the eyeglass lens 1 is viewed in a planar viewmay be used, instead of the X-axis.

The left vertical axis indicates a value of astigmatism (and averagepower), and the units thereof are in diopter.

The right axis indicates the height of the coating film convex portion11 or the base material convex portion 6, and the units thereof are inmm.

Note that the coating film convex portion 11 or the base material convexportion 6 is a portion with 0.3 to 1.3 mm in the horizontal axis. Also,a plot (dotted line) of an average power distribution (i.e., averagepower distribution profile curve), and a plot (broken line) of theheight of the coating film convex portion 11 or the base material convexportion 6 in the Z-axis are also shown.

As shown in FIG. 10, in terms of design, the astigmatism profile curveis substantially constant in the base material convex portion 6 and asubstantially horizontal portion, which is the base portion, and only aportion between the base material convex portion 6 and the base portionhas a shape different from a spherical shape. Thus, only this portionhas a high astigmatism value.

On the other hand, as shown in FIG. 11, with the astigmatism profilecurve for the actual coating film convex portion 11 and the vicinitythereof, astigmatism relatively increases in a comparatively wide rangein the X-axis direction between the coating film convex portion 11 andthe base portion (the vicinity of X=0.3 mm and the vicinity of X=1.3mm). This indicates that the portion located between the coating filmconvex portion 11 and the base portion has a shape that is differentfrom a spherical shape in a comparatively wider range, compared to thatshown in FIG. 10, which is a designed value.

One of the causes of stray light rays is that the shape changesexcessively slowly from the base portion at the base of the coating filmconvex portion 11. That is to say, if the base portion and the coatingfilm convex portion 11 are clearly separated from each other, one of thecauses of stray light rays can be eliminated, and thus the effect ofsuppressing near-sightedness can be sufficiently exhibited even after acoating film is formed on the lens base material 2. In view of this, theastigmatism profile curve is utilized to prove that there are not manyportions having a halfway shape, which is one of the causes of straylight rays, between the base portion and the coating film convex portion11. That is to say, the degree of a change (i.e., a gradient change) inthe shape of the base of the coating film convex portion 11 is definedusing the astigmatism profile curve for the coating film convex portion11.

As the name suggests, the peak width at half of the value (in diopters)of the peak apex point may be used for the full width at half maximumshown in FIG. 11 pertaining to the actual eyeglass lens. In FIG. 11, forexample, the full width at half maximum is about 0.10 mm in the vicinityof X=0.3 mm and in the vicinity of X=1.3 mm.

By defining the full width at half maximum of the astigmatism profilecurve as 0.20 mm or less, it is shown that the shape thereof rapidlychanges from the base portion toward the coating film convex portion 11,and thus the eyeglass lens 1 of one aspect of the present disclosure cansufficiently exhibit the effect of suppressing near-sightedness.

It is preferable that the coating film includes a λ/4 film (not shown)that is in contact with the lens base material 2, the hard coating film8 formed on the λ/4 film, and the antireflection film 10 formed on thehard coating film 8.

There is no limitation to the λ/4 film as long as the λ/4 film is a filmthat optically has a thickness of λ/4, and a film that is used for anantireflection filter may also be used. A urethane resin (having arefractive index n of 1.54) may be used as the λ/4 film as one specificexample, and the thickness thereof may be 70 to 90 nm.

There is no particular limitation to the hard coating film 8 as long asthe scratch resistance of the eyeglass lens 1 can be improved. A siliconcompound (having a refractive index n of 1.50) may be used as the hardcoating film 8 as one specific example, and the thickness thereof may be1.5 to 1.9 μm.

A known antireflection film may be used as the antireflection film 10.

It is preferable that the refractive index of the lens base material 2is higher than that of the λ/4 film, and the refractive index of the λ/4film is higher than that of the hard coating film 8.

The following describes specific contents other than the above-describedcontents.

[Lens Base Material 2]

Aspects of the size of the base material convex portion 6 and thearrangement of the plurality of base material convex portions 6 on thesurface of the lens base material 2 are not particularly limited, andcan be determined from the viewpoint of external visibility of the basematerial convex portion 6, designability given by the base materialconvex portion 6, adjustment of the refractive power by the basematerial convex portion 6, and the like, for example. The height of thebase material convex portion 6 may be 0.1 to 10 μm, for example, and theradius of curvature of the surface of the base material convex portion 6may be 50 to 250 mmR, for example. Also, the distance between adjacentbase material convex portions 6 (the distance between an end portion ofa given base material convex portion 6 and an end portion of a basematerial convex portion 6 that is adjacent to this base material convexportion 6) may be substantially the same as the radius of the basematerial convex portion 6, for example. Also, the plurality of basematerial convex portions 6 can be evenly arranged in the vicinity of thecenter of the lens, for example.

Various lens base materials 2 that are usually used for the eyeglasslens 1 can be used as the lens base material 2. The lens base material 2may be a plastic lens base material or a glass lens base material, forexample. The glass lens base material may be a lens base material madeof inorganic glass, for example. From the viewpoint of light in weightand unlikely to crack, a plastic lens base material is preferable as thelens base material 2. Examples of the plastic lens base material includestyrene resins such as (meth)acrylic resins, allyl carbonate resins suchas polycarbonate resins, allyl resins, diethylene glycol bis(allylcarbonate) resin (CR-39), vinyl resins, polyester resins, polyetherresins, urethan resins obtained through a reaction between an isocyanatecompound and a hydroxy compound such as diethylene glycol, thiourethaneresins obtained through a reaction between an isocyanate compound and apolythiol compound, and cured products (generally called transparentresins) obtained by curing a curable composition containing a (thio)epoxy compound having one or more disulfide bonds in the molecule. Thecurable composition may be referred to as a “polymerizable composition”.An undyed base material (colorless lens) or a dyed base material (dyedlens) may be used as the lens base material 2. Although there are noparticular limitations to the thickness and the diameter of the lensbase material 2, the lens base material 2 may have a thickness (thecentral wall thickness) of about 1 to 30 mm, and have a diameter ofabout 50 to 100 mm, for example. The refractive index of the lens basematerial 2 may be set to about 1.60 to 1.75, for example. However, therefractive index of the lens base material 2 is not limited to theabove-described range, and may be in the above-described range or may beseparated vertically from the range. In the present disclosure and thisspecification, the “refractive index” refers to a refractive index forlight having a wavelength of 500 nm. The lens base material 2 can beformed using a known forming method such as cast polymerization. Thelens base material 2 having the base material convex portions 6 on atleast one surface can be obtained by forming the lens base material 2through cast polymerization, using a mold having a molding surfaceprovided with a plurality of recesses, for example.

[Coating Film]

An example of one aspect of the coating film formed on a surface of thelens base material 2 having the base material convex portions 6 is acured film formed by curing a curable composition containing a curablecompound. Such a cured film is generally called a hard coating film 8,and contributes to improving the durability of the eyeglass lens 1. Thecurable compound refers to a compound having a curable functional group,and the curable composition refers to a composition containing one ormore curable compounds.

Examples of one aspect of the curable composition for forming the curedfilm include curable compositions containing an organosilicon compoundas a curable compound, and curable compositions containing metal oxideparticles together with an organosilicon compound. An example of thecurable composition that can form the cured film is a curablecomposition disclosed in JP 563-10640A.

Also, examples of one aspect of organosilicon compound may includeorganosilicon compounds represented by General Formula (I) below andhydrolysates thereof.

(R¹)_(a)(R³)_(b)Si(OR²)_(4−(a+b))  (I)

In General Formula (I), R¹ represents an organic group having aglycidoxy group, an epoxy group, a vinyl group, a methacryloxy group, anacryloxy group, a mercapto group, an amino group, a phenyl group, or thelike, R² represents an alkyl group having 1 to 4 carbon atoms, an acylgroup having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbonatoms, R³ represents an alkyl group having 1 to 6 carbon atoms or anaryl group having 6 to 10 carbon atoms, and a and b each represent 0 or1.

The alkyl group having 1 to 4 carbon atoms represented by R² is a linearor branched alkyl group, and specific examples thereof include a methylgroup, an ethyl group, a propyl group, and a butyl group.

Examples of the acyl group having 1 to 4 carbon atoms represented by R²include an acetyl group, a propionyl group, an oleyl group, a benzoylgroup.

Examples of the aryl group having 6 to 10 carbon atoms represented by R²include a phenyl group, a xylyl group, and a tolyl group.

The alkyl group having 1 to 6 carbon atoms represented by R³ is a linearor branched alkyl group, and specific examples thereof include a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group,and a hexyl group.

Examples of the aryl group having 6 to 10 carbon atoms represented by R³include a phenyl group, a xylyl group, and a tolyl group.

Specific examples of the compound represented by General Formula (I)above includes the compounds disclosed in paragraph 0073 of JP2007-077327A.

The organosilicon compound represented by General Formula (I) has acurable group, and thus the hard coating film 8 can be formed as a curedfilm by performing a curing process after a composition is applied.

Metal oxide particles may contribute to adjusting the refractive indexof a cured film and improving the hardness of a cured film. Specificexamples of the metal oxide particles include particles of tungstenoxides (WO₃), zinc oxide (ZnO), silicon oxide (SiO₂), aluminum oxide(Al₂O₃), titanium oxide (TiO₂), zirconium oxide (ZrO₂), tin oxide(SnO₂), beryllium oxide (BeO), antimony oxide (Sb₂O₅), and the like, andone type of metal oxide particles can be used alone, or two or moretypes of metal oxide particles can be used in combination. The particlesize of the metal oxide particles is preferably in a range of 5 to 30 nmfrom the viewpoint of improving scratch resistance and opticalproperties of a cured film. The content of metal oxide particles in acurable composition can be set as appropriate in consideration of therefractive index and the hardness of a cured film to be formed, andusually, may be set to about 5 to 80 mass % with respect to the solidcontent of the curable composition. Also, the metal oxide particles arepreferably colloidal particles from the viewpoint of dispersibility in acured film.

The cured film can be formed by forming a covering film by directlyapplying or indirectly applying via another film, to a surface of thelens base material 2 having the base material convex portions 6, acurable composition prepared by mixing the above-described componentsand optional components such as an organic solvent, a surfactant(leveling agent), and a curing agent as needed, and performing a curingprocess (e.g., heating and/or photoirradiation) on the covering filmaccording to the type of curable compound. Application of a curablecomposition will be described later in detail. If a curing process isperformed through heating, for example, a curing reaction of a curablecompound in a covering film can proceed by disposing the lens basematerial 2 provided with the film coated with the curable composition inan environment having an ambient temperature of 50° C. to 150° C. forabout 30 minutes to 2 hours.

From the viewpoint of application suitability for spin coating, theviscosity of a curable composition for forming a coating film on thesurface of the lens base material 2 having the base material convexportions 6 is preferably in a range of 1 to 50 mPa·s, more preferably ina range of 1 to 40 mPa·s, and even more preferably in a range of 1 to 20mPa·s. The viscosity in the present disclosure and this specificationrefers to the viscosity at a liquid temperature of 25° C.

Also, a coating film that is generally called a primer film andcontributes to improving adherence between layers is an example of oneaspect of the coating film formed on the surface of the lens basematerial 2 having the base material convex portions 6. Examples of acoating liquid capable of forming such a coating film includecompositions (referred to as a “dry solidifying composition”hereinafter) in which a resin component such as a polyurethane resin isdispersed in a solvent (water, an organic solvent, or a solvent obtainedby mixing them). Solidification of such a composition proceeds byremoving a solvent through drying. Drying can be performed through adrying process such as air drying or heat drying.

From the viewpoint of application suitability for spin coating, theviscosity of a dry solidifying composition for forming a coating film onthe surface of the lens base material 2 having the base material convexportions 6 is preferably in a range of 1 to 50 mPa·s, more preferably ina range of 1 to 40 mPa·s, and even more preferably in a range of 1 to 20mPa·s.

[Supply of Coating Liquid]

A coating liquid for forming a coating film on the surface of the lensbase material 2 having the base material convex portions 6 is suppliedthrough spin coating. When the coating liquid is applied through spincoating, it is possible to inhibit a coating film from having an unevenfilm thickness due to liquid building up around the base material convexportions 6. The coating liquid can be applied through spin coating byplacing the lens base material 2 in the spin coater with the surfacethereof having the base material convex portions 6 facing verticallyupward, and supplying the coating liquid onto the surface from above(e.g., discharging the coating liquid from a nozzle arranged above thesurface) in a state in which the lens base material 2 is rotated on thespin coater, for example. Here, from the viewpoint of forming a coatingfilm having a more even thickness, the rotational speed of the lens basematerial 2 in the spin coating is preferably in a range of 10 to 3000rpm (rotations per minute), more preferably in a range of 50 to 2500rpm, and even more preferably in a range of 100 to 2000 rpm.

It is possible to form a coating film by performing processes (e.g., acuring process, a drying process, and the like) according to the type ofcoating liquid after the coating liquid is applied.

The film thickness of the coating film formed through theabove-described steps may be in a range of 0.5 to 100 μm, for example.However, the film thickness of the coating film is determined dependingon the functions required for the coating film, and is not limited tothe above-described exemplary range.

It is also possible to form one or more coating films on the coatingfilm. Examples of such coating films include various coating films suchas the antireflection film 10, water repellent or hydrophilicantifouling films, and antifogging films. A known technique can beapplied as a method for forming these coating films.

Also, if one of the surfaces of the lens base material 2 has no basematerial convex portion 6, it is also possible to form one or morecoating films on such surfaces of the lens base material 2. Examples ofsuch a coating film include various coating films that are generallyprovided on the eyeglass lens 1 (e.g., the hard coating film 8, a primerfilm, the antireflection film 10, an antifouling film, an antifoggingfilm, and the like), and it is possible to apply a known technique to amethod for forming these coating films.

In addition to or in place of the above-described specification of theeyeglass lens of one aspect of the present disclosure, the followingprovisions may also be used.

In one aspect of the present disclosure, the maximum absolute value ofdifferences in the lens thickness direction between the shape of thecoating film convex portion and the shape of the base material convexportion is 0.1 μm or less (preferably, 0.06 μm or less).

The following describes advantages for defining the above-describeddifference.

Even if the coating film is formed on the lens base material 2 and thecoating film convex portion 11 has a more obtuse shape than the basematerial convex portion 6 does, at least a vertex portion of the coatingfilm convex portion 11 has a shape following the base material convexportion 6.

That is to say, in one aspect of the present disclosure, thesubstantially partially spherical shape of the actual coating filmconvex portion 11 is compared to the partially spherical shape of theactual lens base material 2.

FIG. 12A is a schematic cross-sectional view showing the coating filmconvex portion 11 and the base material convex portion 6 of the actualeyeglass lens 1. FIG. 12B is a schematic cross-sectional view in whichthe vertex of the coating film convex portion 11 is matched with thevertex of the base material convex portion 6. The solid line indicatesthe coating film convex portion 11 of the actual eyeglass lens 1, thebroken line indicates the base material convex portion 6, and a verticalline portion indicates the difference in the lens thickness directionbetween the shape of the coating film convex portion and the shape ofthe base material convex portion.

In FIG. 12B, the vertex of the coating film convex portion 11 is matchedwith the vertex of the base material convex portion 6, and then thedifference in the lens thickness direction (an optical axis method)between the actual base material convex portion 6 and the coating filmconvex portion 11 of the actual eyeglass lens 1, from a protrusion startportion that protrudes from the base portion of the base material convexportion 6 to a protrusion end portion via the vertex.

If the maximum absolute value of the differences is 0.1 μm or less(preferably 0.06 μm or less), it is deemed that the coating filmfaithfully follows the shape of the base material convex portion 6present below the coating film. It was found that as a result, theeffect of suppressing near-sightedness can be sufficiently exhibited.The effect of suppressing near-sightedness can be sufficiently exhibitedby applying this provision. Note that the similarity ratio between theshape of the coating film convex portion 11 and the shape of the basematerial convex portion 6 may be defined.

With the above-described one aspect of the present disclosure, a casewas described in which the maximum absolute value in the lens thicknessdirection between a spherical surface that is optimally approximated tothe shape of the coating film convex portion 11 and the shape of theactual coating film convex portion 11 was set to 0.1 μm or less. On theother hand, the eyeglass lens 1 according to the present disclosure isnot limited to the provision of this difference. In short, the aim ofthe present disclosure is that a convex portion present on the outermostsurface of the eyeglass lens 1 located on the side on which the basematerial convex portions 6 are provided causes rays that have enteredthe eyeglass lens 1 to converge at the position B that is closer to theobject than the predetermined position A is even after a coating film isformed, and this aim is novel.

The above-described technical ideas of the eyeglass lens of one aspectof the present disclosure can also be applied to an eyeglass lens havinga farsightedness suppression function. Specifically, “convex portions”of the coating film convex portion 11 and the base material convexportion 6 are changed to “concave portions”. Accordingly, a coating filmconcave portion can cause rays that have entered the eyeglass lens toconverge at a position B′ that is located on the “eyeball side” of thepredetermined position A. By changing the “convex portion” to a “concaveportion” in the above-described eyeglass lens of one aspect of thepresent disclosure and changing a configuration such that rays convergeat a position B′ that is located on the “eyeball side” of thepredetermined position A, the eyeglass lens has a far-sightednesssuppression function.

LIST OF REFERENCE NUMERALS

-   -   1 Eyeglass lens    -   2 Lens base material    -   3 Object-side surface (convex surface)    -   4 Eyeball-side surface (concave surface)    -   6 Base material convex portion    -   8 Hard coating film    -   10 Antireflection film    -   11 Coating film convex portion    -   20 Eyeball    -   20A Retina    -   30 Eyeglass lens model    -   32 Eyeball model    -   32A Retina    -   33 Object-side surface (convex surface) on model    -   36 Coating film convex portion on model

1. An eyeglass lens configured to cause rays from a point source atinfinity that enter the eyeglass lens at an object side of the eyeglasslens to exit the eyeglass lens from an eyeball side of the eyeglass lensand converge at a predetermined position A, the eyeglass lenscomprising: a lens base material having an object-side surface and aneyeball-side surface, at least one of the object-side surface and theeyeball-side surface including a plurality of base material convexportions; and a coating film covering the at least one of theobject-side surface and the eyeball-side surface that includes theplurality of base material convex portions, wherein, at the at least oneof the object-side surface and the eyeball-side surface that includesthe plurality of base material convex portions, a correspondingoutermost surface of the eyeglass lens includes a plurality of convexportions, and wherein, for each of the plurality of convex portions, ashape of the convex portion approximates a shape of a corresponding oneof the plurality of base material convex portions, and wherein theplurality of base material convex portions is configured to cause raysfrom a point source at infinity that have entered the eyeglass lens toconverge at a plurality of positions B that are closer to the objectthan the predetermined position A is.
 2. The eyeglass lens according toclaim 1, wherein the coating film includes a plurality of coating filmconvex portions, and wherein, for each of the plurality of coating filmconvex portions: a shape of an outermost surface of the coating filmconvex portion originates from a shape of an outermost surface of acorresponding one of the plurality of base material convex portions, andthe coating film convex portion is configured to cause rays from a pointsource at infinity that have entered the eyeglass lens to converge at acorresponding one of the plurality B of positions that is closer to theobject than the predetermined position A is, and a maximum absolutevalue of differences in a lens thickness direction between a sphericalsurface that is optimally approximated to a shape of the coating filmconvex portion and the shape of the actual coating film convex portionis 0.1 μm or less.
 3. The eyeglass lens according to claim 2, whereineach of the plurality B of positions is closer to the object than thepredetermined position A is by an amount in a range of more than 0 mmand 10 mm or less.
 4. The eyeglass lens according to claim 2, wherein,out of a large number of rays from a point source at infinity thatevenly enter a predetermined range of the object side of the eyeglasslens and pass through the coating film, the proportion that pass throughneither the vicinity of the predetermined position A nor the vicinity ofany of the plurality B of positions is less than or equal to 30% of thelarge number of rays.
 5. The eyeglass lens according to claim 2,wherein, for at least one of the plurality of coating film convexportions, the full width at half maximum of a profile curve of cylinderpower at a base of the coating film convex portion in a distribution ofcylinder power for the shape of the outermost surface of the coatingfilm is 0.20 mm or less.
 6. The eyeglass lens according to claim 1,wherein the coating film includes a λ/4 film that is in contact with thelens base material, a hard coating film formed on the λ/4 film, and anantireflection film formed on the hard coating film.
 7. The eyeglasslens according to claim 6, wherein a refractive index of the lens basematerial is higher than that of the λ/4 film, and a refractive index ofthe λ/4 film is higher than that of the hard coating film.